1. Field of the Invention
The present invention generally relates to electronic testing units, and more particularly to a testing unit designed to analyze headsets used in conjunction with communications equipment.
2. Description of the Prior Art
Anyone who has ever been in a large office, or worked in the communications industry, is familiar with the headsets used by receptionists and operators which allow discussion on telephone lines while keeping the hands free. These headsets typically have "top" and "bottom" portions, the top portion being that part of the headset that actually rests on the head, including the earpiece/speaker and the mouthpiece/microphone, and the bottom portion being an amplifier stage (sometimes with an auxiliary power pack) which is connected to the top portion via a normal telephone cord.
The companies which manufacture headsets, as well as certain regulatory agencies, like the FCC, have established performance specifications for these units. Specifically, manufacturers and users are concerned with reception and transmission quality (in terms of amplitude retention as well as distortion), reception limiting (so that an earpiece/speaker does not deafen the user), and current consumption of the headsets. Therefore, there is a clear need for a device which can perform all of these tests on headsets as they leave the factory, as well as for follow-up maintenance testing.
Certainly, devices have been invented which are related to testing of communications equipment. For example, U.S. Pat. No. 3,927,281 issued to F. Bradley, discloses an instrument for measuring harmonic distortion in telephone transmissions. Another U.S. Pat. No. 4,301,536 issued to Favin et al., describes a system for measuring frequency response and distortion in a network employing a 21-tone signal. U.S. Pat. No. 4,340,854 issued to Jones et al., discusses a unique distortion measurement system employing a two-state variable filter circuit. Another distortion measuring device is depleted in U.S. Pat. No. 4,417,310 issued to K. Sugihara, incorporating a digital filtering technique. Another patent issued to Favin et al., U.S. Pat. No. 4,417,337, sets forth a method for generating a measurement of various transmission parameters for a communications network. Finally, U.S. Pat. No. 4,623,837 issued to Efron et al., shows a system for automated product testing of audio/video units.
Unfortunately, none of these devices is directed to the testing of telephone headsets. In fact, the inventor knows of only one apparatus designed for this purpose, namely the headset tester manufactured by Plantronics, of Santa Cruz, Calif. This device, however, has several drawbacks. First of all, it possesses no capability of measuring distortion. Furthermore, it sends a signal at only one frequency and does not cover the entire audible spectrum. Finally, and perhaps most importantly, it does not provide automatic testing capability. It would, therefore, be desirable and advantageous to devise a headset tester which can perform all of the aforementioned tests, and which would also be universal in the sense of being able to test any conventional headset. For factory testing, the device should also be able to perform automated test sequences.